CANDIDATE GENE FOR DIABETIC NEPHROPATHY--MEPRIN BETA

这项研究的长期目标是了解 蛋白酶在肾脏疾病的发展，特别是在 DN的病理生理学 皮马属植物的分离和连锁分析 印度人已经确定了18号染色体上的一个区域， 主要影响DN的患病率。 唯一的候选基因 在该区域中鉴定出的是meprin-b的结构基因， 位于刷状缘的膜金属蛋白酶的亚单位 肾近端小管的膜。 Meprin-b能够切割 多种生物活性肽和蛋白质，包括胰高血糖素， 胰岛素B链，甲状旁腺激素，胃泌素，胆囊收缩素，蛋白质 激酶A、明胶和胶原蛋白。 此应用程序的重点是 检验meprin-b基因（结构或 调节区）导致可变表达， meprin-b蛋白的靶向、活性或稳定性，并且这 与DN的易感性有关。 除了分析DNA 患有晚期DN或长期糖尿病的皮马印第安人 在没有肾病的情况下，过度表达或 将开发并检查meprin-b基因的无效肾脏 功能和对DN的易感性。 申请的具体目的 是：1）分析来自皮马印第安人的meprin-b基因， DN和未受影响的个体; 2）确定是否鉴定出突变 在肾病患者中，影响生物合成、定位 稳定性或转染实验中meprin-b的活性，和 确定免疫化学定位是否存在异常 糖尿病肾病患者肾皮质样本中meprin-b的含量; 3） 在转基因小鼠中过表达meprin-b基因，并确定 对肾功能和DN易感性的影响 链脲霉素或2型糖尿病的遗传模型;和4） 研究meprin-b基因敲除小鼠的肾功能， DN易感性。 这些研究将确定MEPRIN-B是否 基因与人类对DN的易感性相关，并提供 动物模型，以确定这种蛋白酶在正常肾脏中的作用 以及对肾脏疾病的易感性。

The long-term goals of this research are to understand the role of proteases in the development of renal diseases, and particularly in the pathophysiology of DN. Recent segregation and linkage analyses of Pima Indians have identified a region on chromosome 18 indicated to have a major effect on the prevalence of DN. The only candidate gene identified in this region was the structural gene for meprin-b, a subunit of a membrane metalloprotease localized to the brush border membranes of renal proximal tubules. Meprin-b is capable of cleaving a variety of bioactive peptides and proteins, including glucagon, insulin B chain, parathyroid hormone, gastrin, cholecystokinin, protein kinase A, gelatin, and collagen. The focus of this application is to test the hypothesis that variation in the meprin-b gene (structural or regulatory regions) in Pima Indians results in the variable expression, targeting, activity, or stability of the meprin-b protein, and that this is related to the susceptibility to DN. In addition to analyzing DNA from Pima Indians with advanced DN or with long-standing diabetes without nephropathy, genetically modified mice that overexpress or are null for the meprin-b gene will be developed and examined for kidney function and susceptibility to DN. The Specific Aims of the application are to: 1) analyze the meprin-b gene from Pima Indians that developed DN and unaffected individuals; 2) determine whether mutations identified in patients with nephropathy affect biosynthesis, localization, stability, or activity or meprin-b in transfection experiments, and determine whether there are abnormalities in immunochemical localization of meprin-b in kidney cortex samples from-individuals with DN; 3) overexpress the meprin-b gene in transgenic mice, and determine the effects on kidney function and susceptibility to DN induced by streptozocin or in a genetic model of type 2 diabetes; and 4) investigate the meprin-b knock-out mouse for kidney function and susceptibility to DN. These studies will establish whether the meprin-b gene is associated with susceptibility to DN in humans, and provide animal models to determine the role of this proteinase in normal kidney and in susceptibility to renal disease.